Recently, I bought a shiny new set of Chinesium gear cutters, to make the back gears for my Boxford. They sat, lonelyly, in their box for a while, as I didn't have a suitable holder for them... So, time to rectify that!
I bought a lump of 50mm AF mild steel hex bar. Hacked it to length in the hacksaw, then drilled/bored out a recess in the back. My thinking was, if I get the nut all the way in, it'll stand on its back face too. As it happens, that didn't work out, although there's no reason it couldn't in the future. (pic 1)
After that, I turned it around and drilled it 1/2" all the way through (
convinced that my drawbar was 1/2" UNF.... not the 7/16" UNF it
actually is! Hey ho, it's not a problem this time). Then bored all but around 1/4" to the R8 shank size + a few thou clearance.
The R8 blank arbor I bought from the lovely chaps at RDG Tools had a suitable flat face on it, so pinning it in the hole with a live centre allowed me to set up the compound slide to the exact taper - lots of swearing at that job I can tell you, but I got there in the end & bored out enough of a taper that maybe 2mm of the collet ends up sticking out of the nose when it's tightened up.
Penultimate job - turn, thread, and cut the hex end into a custom nut, which pulls the collet tight. Finally; turn the end of an M6 bolt down until it fits in the slot of my most recalcitrant collet, drill & tap a suitable hole in the collet block, apply screw, and tada!
(pics 2-5).
It worked out very well, and can be dialled in on the 3-jaw to around 0.002 TIR, given a big enough hammer
